title: Evolution of paedomorphosis in plethodontid salamanders: ecological correlates and re-evolution of metamorphosis.
abstract: Life-history modes can profoundly impact the biology of a species, and a classic example is the dichotomy between metamorphic (biphasic) and paedomorphic (permanently aquatic) life-history strategies in salamanders. However, despite centuries of research on this system, several basic questions about the evolution of paedomorphosis in salamanders have not been addressed. Here, we use a nearly comprehensive, time-calibrated phylogeny of spelerpine plethodontids to reconstruct the evolution of paedomorphosis and to test if paedomorphosis is (1) reversible; (2) associated with living in caves; (3) associated with relatively dry climatic conditions on the surface; and (4) correlated with limited range size and geographic dispersal. We find that paedomorphosis arose multiple times in spelerpines. We also find evidence for re-evolution of metamorphosis after several million years of paedomorphosis in a lineage of Eurycea from the Edwards Plateau region of Texas. We also show for the first time using phylogenetic comparative methods that paedomorphosis is highly correlated with cave-dwelling, arid surface environments, and small geographic range sizes, providing insights into both the causes and consequences of this major life history transition.
authors.affiliation: Department of Biological Science, University of Tulsa, Tulsa, Oklahoma, 74104. ron-bonett@utulsa.edu.
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Bonett
authors.forename: Michael A
authors.initials: MA
authors.lastname: Steffen
authors.forename: Shea M
authors.initials: SM
authors.lastname: Lambert
authors.forename: John J
authors.initials: JJ
authors.lastname: Wiens
authors.forename: Paul T
authors.initials: PT
authors.lastname: Chippindale
mesh_terms: D000818:Animals; D059552:Caves; D002980:Climate; D019143:Evolution, Molecular; D049810:Genetic Speciation; D008675:Metamorphosis, Biological / Q000235:genetics*; D010802:Phylogeny; D014562:Caudata / Q000145:classification / Q000235:genetics* / Q000254:growth & development
keywords: Amphibians; biogeography; climate; development; life history; phylogeny